There are about 70 million baby boomers in the United States, many now over age 65. As people age, rates of cardiovascular and cerebrovascular diseases rise, leading to more use of blood thinners such as warfarin. At the same time, older adults face a higher risk of head injuries and brain bleeding, especially after falls.
Falls are the leading cause of injury and death in older adults, causing 38,000 deaths and 3 million emergency department visits in 2021. The health care cost for non-fatal falls in this group reached $80 billion in 2020, up sharply from 2015.
While anticoagulants protect against heart and vessel problems, they increase the risk of serious bleeding, particularly, brain hemorrhages after head trauma. It is widely believed that supratherapeutic warfarin activity increases the chance of brain hemorrhage after trauma. Current guidelines call for extra monitoring and repeat brain scans for patients on warfarin after head injuries.
Warfarin is considered especially challenging because maintaining safe blood-thinning levels – measured by the International Normalized Ratio (INR) – can be difficult. When INR is too high, bleeding risk rises significantly. Although many studies link high INR with increased bleeding risk, most have been small or limited.
To address a critical gap in emergency care, researchers at Florida Atlantic University 's Charles E. Schmidt College of Medicine conducted a new study to determine whether very high INR levels increase the risk of brain bleeding following a fall-related head injury in adults aged 65 and older who take warfarin. Conducted over one year at two Level I trauma centers in South Florida, the study examined 2,686 patients admitted to the emergency department due to a fall. Researchers compared outcomes between patients who were on warfarin before their injury and those who were not taking any blood thinners.
Results of the study, published in the American Journal of Emergency Medicine , found that being on warfarin, even at higher blood-thinning levels, did not significantly increase the risk of brain bleeding after blunt head trauma. In fact, patients with poorly controlled, low warfarin activity had the highest bleeding risk. This challenges common assumptions and underscores the importance of proper anticoagulation management rather than avoiding anticoagulants altogether.
Overall, about 11% of the patients studied experienced brain bleeding after head trauma. Among those not on blood thinners, about 6% had brain bleeds, compared to around 7% of patients on warfarin. Bleeding rates were similar between patients with INR levels above and below 3.0.
Notably, patients with lower-than-recommended INR levels had the highest rates of brain bleeding – nearly 20%. Those within or slightly above the therapeutic range had lower rates, and no brain bleeds occurred in patients with critically high INR levels (above 5).
"Data from our study suggest supratherapeutic INR levels may not increase intracranial hemorrhage risk as much as we previously believed," said Richard Shih , M.D., senior author and a professor of emergency medicine, FAU Schmidt College of Medicine. "This raises important questions about current emergency care protocols and how we monitor these patients. It's critical to re-examine our approach to managing anticoagulation in older adults after head trauma to provide the safest, most effective care without unnecessary tests or hospital stays. It's our hope that findings from our research will help improve patient outcomes while reducing health care costs."
Researchers reviewed each patient's medical history, physical exam findings, blood tests and CT scans, and followed up with phone calls and chart reviews two weeks after the injury to identify any delayed brain bleeding. The primary goal was to determine whether bleeding occurred within 14 days, confirmed by CT scans during the hospital stay. The study also looked at the type and severity of brain bleeds, patient outcomes, length of hospitalization, and survival rates.
"With clearer evidence on how blood-thinning levels impact outcomes, health care providers can develop more precise guidelines for follow-up care and monitoring – optimizing resources and improving patient management," said Lisa Clayton , D.O., co-author and associate dean for graduate medical education and chair, FAU Department of Emergency Medicine . "In South Florida, where our older population is rapidly growing, this research is especially valuable. It could help emergency teams to make smarter, more balanced decisions that protect patients from serious complications without unnecessary interventions, advancing patient-centered care in a region facing this critical public health challenge."
Study co-authors are Chelsea Caplan, first author and a medical student at the University of Miami Miller School of Medicine; Gabriella Engstrom , Ph.D., research assistant professor of emergency medicine; Mike Wells , Ph.D., research assistant professor of emergency medicine; Scott M. Alter , M.D., assistant dean for clinical research and associate professor of emergency medicine; and Joshua J. Solano , M.D., an associate professor of emergency medicine; all within the FAU Schmidt College of Medicine; Eric Bruno, M.D., University of Tennessee Health Science Center; and Timothy P. Buckley , M.D., an assistant professor of emergency medicine and quality improvement director, FAU Schmidt College of Medicine.
The research was supported by The Florida Medical Malpractice Joint Underwriting Association Grant for Safety of Health Care Services Grant RFA #2018-01, "Geriatric Head Trauma Short Term Outcomes Project (The GREAT STOP)."
- FAU -
About the Charles E. Schmidt College of Medicine:
Florida Atlantic University's Charles E. Schmidt College of Medicine is one of approximately 159 accredited medical schools in the U.S. The college was launched in 2010, when the Florida Board of Governors made a landmark decision authorizing FAU to award the M.D. degree. After receiving approval from the Florida legislature and the governor, it became the 134th allopathic medical school in North America. With more than 170 full and part-time faculty and more than 1,300 affiliate faculty, the college matriculates 80 medical students each year and has been nationally recognized for its innovative curriculum. The college offers M.S. (thesis and non-thesis) and Ph.D. programs in biomedical science, along with a certificate in genomics and precision medicine. Taught by top researchers, the curriculum combines cutting-edge coursework with hands-on learning, preparing graduates for careers in medicine, research, industry, and academia. To further Florida Atlantic's commitment to increase much needed medical residency positions in Palm Beach County and to ensure that the region will continue to have an adequate and well-trained physician workforce, the FAU Charles E. Schmidt College of Medicine Consortium for Graduate Medical Education (GME) was formed in fall 2011 with five leading hospitals in Palm Beach County. The consortium currently has five Accreditation Council for Graduate Medical Education (ACGME) accredited residencies including internal medicine, surgery, emergency medicine, psychiatry, and neurology, and five fellowships in cardiology, hospice and palliative care, geriatrics, vascular surgery, and pulmonary disease and critical care medicine. The college also manages the Florida Atlantic University Medical Group, offering comprehensive primary care, and the Marcus Institute of Integrative Health specializes in integrative pain management, precision therapies, and mental health. A 2023 partnership with Broward Health expands academic medicine, clinical training, and research opportunities.
About Florida Atlantic University:
